The PJM Interconnection is getting close to approving rules governing microgrids operated by distribution utilities or third parties on their behalf — what it calls public distribution microgrids.
After being approved by various stakeholder panels, the PJM’s Markets and Reliability Committee (MRC) is set to review the proposed rules at a December 17 meeting and potentially endorse them in January.
Once endorsed at the MRC the microgrid rules would be published in PJM’s Manual 14D and would become effective, according to Andrew Levitt, a senior market design specialist for the grid operator.
The rules remove a few PJM-side barriers to the development of a particular type of public microgrid on the distribution system, Levitt said.
The planned rules only apply to distribution-level microgrids, according to a December 3 presentation by the grid operator’s staff. The microgrids may not include any bulk electric system components or transmission facilities.
PJM defines public distribution microgrids
Under the planned rules, public distribution microgrids, or PDMs, must include load, one or more generators, one or more switches for isolating from and connecting to the broader grid, and a microgrid controller.
A PDM generator must sell its power to PJM, which operates the grid and power markets in 13 Mid-Atlantic and Midwest states and the District of Columbia.
When in island mode, the electric distribution company can operate the microgrid at the wholesale or retail level, according to the presentation.
The proposed rules require the microgrid generator operators to notify PJM of the start and end of planned and actual islanded conditions as soon as possible. To facilitate the notification, the microgrid operator must provide all necessary information to the microgrid generator operator on an ongoing basis, PJM staff said.
No islanding for economic reasons
PJM is proposing to bar utility microgrids from going into island mode for economic reasons, according to the presentation.
The only reasons they could disconnect from the grid would be:
- An emergency situation on the distribution or transmission system
- A situation affecting system restoration
- An emergency on the transmission system in which PJM orders load shedding
- An emergency declaration by local, state or federal authorities
- Testing and distribution facility maintenance
When in island mode, PJM plans to require a microgrid operator to “de-assign” the PDM from any existing ancillary services commitments, the grid operator’s staff said. The operator will be required to make sure the microgrid is not assigned for ancillary services for future intervals unless it is certain it will be connected to the grid in those intervals.
Under the planned rules, a PDM generator must meet existing telemetry requirements for all PJM generators. Also, if it has real-time data on whether it is islanded or not, the generator must provide that information to PJM, according to the presentation.
Also, the planned rules require a PDM operator to give public distribution generators the real-time status of any switching or relay that indicates the status of the utility microgrid.
A transmission owner that is planning, or has a distribution affiliate that is planning, a PDM with automatic separation should provide the grid operator with the details of how the relay would automatically open the switch, according to the presentation.
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